Optical color sensors can be found in most of digital camera system. An incident light is transformed to an electronic signal. Then, the electronic signal is converted and digitized for an image process and recorded by an analog/digital converter.
Unfortunately, optical color sensors suffer from color image aberrations that distort the true color of the image. These aberrations can be caused by the non-uniformity of pixel-to-pixel color transmission resulting from the non-uniformity of color resist flow. Some of the present solutions are discussed below.
One solution is to apply a low viscosity color resist in a unique spin recipe onto a standard passivation surface and attempt to optimize the transmission matching through a photolithography coating process. This process has inherent drawbacks in that the topographical features of the surface of the incoming wafer limit the reduction of non-uniformity that can be achieved.
Another solution involves inserting a spin on the planarization layer between the passivation and the color filter layer. This process suffers from integration issues associated with the bondpad interface. The non-uniformity of the color filter layer is still on the order of about 200 Angstroms peak to trough.
Thus, a need still remains for a system for improving the uniformity of color transmission in optical color sensors. In view of the foregoing, it is increasingly critical that answers be found to these problems.